August 3-6, 2008 Bob Albertini - GovEnergy

Automated Meter Reading 

(AMR) at NAVFAC Midlant

Introduction 

• Bob Albertini 

• Ameresco Federal Solutions 

• balbertini@ameresco.com 

Please remember to fill out and drop off your 

session evaluations. 

Bob Albertini 

August 3-6, 2008

Agenda 

• Project Overview 

• AMR System Components 

• Project Features 

• Project Benefits 

• Lessons Learned 

• Screen Shots 



Project Overview 

• Technical Aspect 

– 7 Bases located in SE Virginia 

– ~1700 Meters 

– 10 Substations 

– System & Manufacturer: 

• Two Way Automatic Communication System 

(TWACS®) 

• Aclara Power Line Systems Inc. 

– Formerly known as Distributed Control Systems, Inc. 

(DCSI) 



Project Locations 



Situation Prior to New System 

• Meter reads performed by high voltage 

electricians 

– Travel time & expense 

– Inefficient use of skilled personnel 

• Meter reads hand entered into billing 

system 

– Many estimates & high bill complaints 

• Impossible to manage or evaluate energy 

consumption data 



Project Overview 

• Financial Aspect 

– Cost: $4.3M 

– Savings: 

• $ 474,000 : Energy (1% per Navy Energy Project Execution Guide) 

• $ 140,000 : Eliminated 2 Funded/Unfilled Positions 

• Contractual Aspect 

– Ameresco designed and installed system 

– Utility Energy Services Contract (UESC) via Virginia 

Natural Gas (VNG) Areawide Contract 



How does TWACS® work? 

Outbound 

Communication 

(Sub Meters) 

Inbound Bit 

1 3 5 7 

V 1 

V 2 

2 4 

6 8 

T A 

Outbound Bit 

T B 

Inbound 

Communication 

(Meters Sub) 



System Overview 

Distribution 

Substation 

TWACS Substation 

Communications Equipment (SCE) 

Power Lines 

(unconditioned) 

Electric Meter w/ TWACs Remote 

Communication Equipment (RCE) 

Central Control Equipment (CCE): 

TWACS Net Server (TNS) Master Station 

CUBIC 

Hardened 

Microwave 

Service to 

Building 

WAN 

Client 

Workstations 

(PC) 

SCADA, Energy 

Management, Outage 

Management Systems 

and/or Other Platforms 



System Components 

• Central Control Equipment (CCE) 

• Provides system control and operation 

• Substation Communications Equipment (SCE) 

• Located at substations 

• Converts and relays TWACS signal between CCE & RCE 

• Communicates with CCE via phone, cable, DSL, microwave 

• Communicates with RCE via utility distribution line 

• Remote Communication Equipment (RCE) 

• TWACS transponder located in utility meter 

• Unique serial number address allows system to isolate and 

communicate with each meter 



TWACS® System Flow of Information 

• Outbound (shown in 

green) 

– TNS to CRU to OMU 

to MTU to Meter (RCE) 

• Inbound (shown in red) 

– Meter to IPU to CRU to 

TNS 



Control Receiving Unit (CRU) 

CRU serves as the 

substation “Supervisor” 

Communicates with 

Master Station 

Controls “outbound” and 

processes “inbound” TWACS 

signals 

Can be configured for 

indoor or outdoor use 

Can handle up to 12 

independent busses or 32 

feeders 



Outbound Modulation Unit (OMU) 

OMU serves as 

TWACS’ “outbound” 

signal generator 

Powered from lowvoltage 

side of MTU 

(480/277 volts) 

Connected to MTU 

through current-limiting 

fuses 

Sends zero-crossing 

information back to CRU 

Communicates to CRU 

through fiber-optic cables 



Modulation Transformer Unit (MTU) 

3 PHASE PADMOUNT 

• MTU steps down 

Bus voltage to 480/277V 

• Supplies power to the 

OMU 

SINGLE PHASE CANS 

• MTU kVA rating depends on: 

- OA rating of Sub Transformer 

- Impedance of Sub Transformer 

- 3- or 4-wire 4 wire Distribution 



Remote Communications Equipment - 

(RCE) 

Commercial Metering 

Transponder (CMT) 

L+G S4/S4e 

Itron Sentinel 

Itron Vectron 

Universal Metering 

Transponder - 

Commercial (UMT) 

Elster A3 

GE KV2c 



Inbound Pickup Unit (IPU) 

• 3 auxiliary current 

transformers in one 

enclosure to provide: 

• Isolation between 

the power system’s 

current transformers 

(CTs) and CRU 

• 200:1 current signal 

level reduction 

• Effective burden = 

0.0055 Ohms per phase 

Termination Panel Inside CRU 



Non-integrated Substation 

Communications Equipment (SCE) 

FDS 

OMU 

CRU 



Integrated Modulation Transformer Unit 

(MTU) Package 

CRU 

MTU 

FDS 

OMU 



Why is TWACS® ideal for 

electric utilities? 

• Provides virtually 100% coverage 

• Effective regardless of customer density, terrain, customer type 

• Uses existing utility infrastructure 

– No dedicated communication network to engineer, construct, or “tune” 

– Handles multiple step-down transformers, and long lines 

• Self-restoring network when distribution system is restored 

• Independent of RF regulatory environment or licensing concerns 

• Minimal incremental investment to add meters 

– No additional network investment is needed 

• Full Two-Way Access to and into each premise 

– Provide immediate benefits and future functions 



Project Features 

• New meters installed at existing meter locations 

• Data collected in 15 minute intervals for 3 phase meters 

– 60 minute intervals for single phase 

• Communication between SCE and CCE over Navy’s 

existing hardened microwave system 

• Data transmitted from every meter every 2 hours 

– Stored in relational database (Oracle database) 

• Metering system communicates with CUBIC via flat file 

import/export 

• Accessible via web-based interface 



Project Benefits 

• Automatic metering and tenant billing 

– Reduced metering costs and administrative efforts 

– Standard billing periods across all tenants/sites 

• Allows for kW Demand rate structure 

• Improved accuracy 

– Reduced tenant high-bill complaints 

– Improved credibility w/ tenants 

• Energy Management 

– Trending 

– Anomalies 

– Target high consumption buildings 



Main Screen 



Typical Screen-Daily Data 



Typical Screen-15 min. Data 



Lessons Learned 

• Communication 

– Housing Privatization 

– Outages for some meter installations 

• Flexibility 

– Solutions to issues in field & contract 

• Strong Team 

– Good Contracting Officer 

– Good subcontractor 



For More Information 

Would you like to know more about this 

session? 

• Bob Albertini 

• Ameresco Federal Solutions 

• balbertini@ameresco.com 

• 708-482-4896 

Don’t forget to fill out and drop off your 

session evaluations!

August 3-6, 2008 Bob Albertini - GovEnergy

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